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American Kestrel
(Falco sparverius)
Banded December 31, 1999 - Indiana
General Information
The colorful American Kestrel, also known as the Sparrow Hawk, killy hawk, or
windhover, is the smallest and most common North American falcon. Its range
extends from Alaska and Canada southward through the Americas to Tierra del
Fuego. Some are migratory, but some pairs will remain and defend a wintering
territory. Kestrels withdraw from their northern most breeding range in the winter.
The American Kestrel is closely related to the European Kestrel.
If you see a small falcon that appears to be hovering on rapid wing beats over a
field or an interstate median, this is most likely the bird.
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The Kestrel is 9-12 inches long, with a wingspan of 20-24.5
inches. Weights range from 3 to 4 ounces, with females slightly larger than males. Kestrels have been clocked at speeds of
nearly 40 mph. Handling this bird is John Schaust, an experienced raptor rehabilitator, and Park Manager and Naturalist for Holiday Park in Indianapolis. |
Figure 1 - John Schaust with American Kestrel
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Figure 2 - American Kestrel Male
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The male Kestrel is a beautiful bird, a fact not usually
appreciated when the birds is seen as a dark silhouette against a bright sky. The long,
slender, pointed wings are blue-gray, and the back and tail are rufous red. A broad, black
band extends across the terminal end of the tail, and a white band extends across the
tip of the tail. |
The vertical black pattern on a white face give the Kestrel the look of having sideburns. Man is the greatest enemy of the
Kestrel. Many are shot, others are killed by house cats, by flying into windows, and by
getting hit by cars. These fatalities are unfortunate, as these birds provide us a great
service by consuming large numbers of destructive rodents and insect pests.
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Figure 3 - American Kestrel
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Figure 4 - American Kestrel
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The eyes of the Kestrel face somewhat forward, providing the
bird great depth perception and enabling it to prey on its favorite foods of mice, voles, small
birds, lizards, grasshoppers, crickets, and other insects. The Kestrel's eyes are far superior to our human eye. They are
sensitive to light in the near ultra-violet spectrum, and allow the bird to see the urine stained trail of a rodent on the grass. The high density of cone receptors allow the bird to see small details at greater distances.
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The upper wing of the male Kestrel is blue-gray with white spotting. When viewed from below, the white spots along the trailing edge of the wing of both males and females are visible as a translucent line of spots. |
Figure 5 - Upper Wing of Male Kestrel
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Figure 6 - Female Wing
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The wing of the female Kestrel is brown wing with many white spots. |
Adult males have a rufous chest with little or no spotting or barring. |
Figure 7 - Breast of Adult Male
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Figure 8 - Breast of Young Male
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Immature males have less rufous, and show barring and spotting in the chest. |
The age of the female American Kestrel can be determined by the width of the black
subterminal band. In mature birds, the black subterminal band is twice as wide as the other black bands on the tail. In immature birds, the subterminal black band is less than twice as wide as the other black bands. |
Figure 9 - Tail of Mature Female Kestrel
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Nesting Behavior
Kestrels are cavity nesters, preferring a natural cavity, a woodpecker hole, or
crevice in a tree. Suitable artificial nest boxes are also used. From 3 to 7 eggs
are incubated primarily by the female for up to 30 days. During this time, the male
brings food to the female, who then feeds the hatchlings. At 20 days, when the
young are able to feed themselves in the nest, both parents hunt food.
Young leave the nest in about 30 days.
Banding Recoveries
The Bird Banding Lab web site reports that between 1955 and 1998, 202,708 American Kestrels were banded. Of these,
3,647 have been recovered, a recovery rate of 1.79%.
Banding studies show that some American Kestrels are migratory, but others
defend a winter territory. They can live up to 6 years in the wild, but most suffer a
fatality in the second year of life, usually in the fall. In captivity, Kestrels have lived
from 14 to 17 years.
If you should recover a banded bird, please report the band number to the Bird Banding Lab by calling 1-800-327-BAND.
Conservation
Kestrel populations appear to be increasing across most of the US. Kestrels provide a valuable service by consuming many destructive rodents and insect
pests. As attractive members of the falcon family, they are an interesting and
aesthetically pleasing component of our natural world, especially to those who
take the time to enjoy their antics.
The shortage of natural cavities for nesting may limit their population size. If you
live in an area where Kestrels occur, consider adding a Kestrel nest box to your
property.
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All images are courtesy of CWBO. All image copyrights are owned by CWBO.
Any use of these images must have permission of CWBO. |
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